The present invention relates generally to reciprocating mowers and, more particularly, to an improved knife section for inclusion on the cutterbar assembly of reciprocating mowers.
Reciprocating mowers are currently found on many crop harvesting machines to sever the crop from the ground and initiate the harvesting process. For example, reciprocating mowers can be found on mower-conditions, windrowers and combine equipment. Reciprocating mowers are also commonly utilized independently of other harvesting machines as a mowing device. A reciprocating mower differs from a rotary type of mower in that the former cuts with a shearing action while the latter cuts via an impact action.
The standard knife section utilized in present day reciprocating mowers is generally triangular in shape and possesses a cutting edge on each of two sides. The cutting edges cooperate with shear surfaces on adjacent mower guards to cut crop material via a shearing type of cutting action. Normally, a plurality of knife sections are riveted at the base thereof to a support bar which extends to connect with a drive mechanism to induce a reciprocating linear motion thereto.
With increasing material costs, the manufacturing of a knife section from significantly less material has been found to be increasingly desirable. However, since each individual knife section is independently attached to the support bar and can be replaced if broken, maintaining the identical exterior dimensions, i.e. thickness, length and width, of a standard knife section has been a problem. Making a knife section from less material also creates the disadvantage of reduced strength and rigidity, particularly in light of the high operating speeds and stresses imposed on the modern day knife section.
In addition, the trend in farm machinery today appears to be one of increasing size and to increase the width of cut of a harvesting machine necessitates an increase in the length of the cutterbar. Adding additional knife sections, to increase the length of the cutterbar, increases the mass inertia of the cutterbar assembly, increases the vibrations transmitted to the rest of the harvesting machine and necessitates a higher energy input to operate the cutterbar assembly.
Previous attempts to lighten the weight of a knife section have resulted in knife sections with a thinner center body section, see U.S. Pat. No. 16,442, or no center body section at all, see U.S. Pat. No. 6,903 and U.S. Pat. No. 2,931,159. However, since the high operating speeds and the high stresses placed on present day reciprocating mowers require that strength and rigidity of the knife section be maintained, such weight reducing inventions have been found to be impractical.
R. Allstatter (see U.S. Pat. No. 103,699 granted May 31, 1870) incorporated a V-shaped rib to increase the strength of a thinner knife section. However, the knife sections in Allstatter are not capable of individually replacing standard knife sections since this rib terminates before reaching the rivet holes and the support bar area; either the base portion would be thinner than the standard knife section or the body portion would be much thicker.